Compressor-unloading means



y 1; 6 H. B. HALVORSEN 1,769,667

COMPRES SOR UNLOADING MEANS Filed Feb. 25, 1924 2 Sheets-Sheet 2 v 5 w E11/.

Patented duty i EQidfi wearer HALBERT B. HALVQRSEN, 3F MICHIGAN II TY,INDIANA, ASSIGNQB T6 SULEWAN NAOHINERY GQMPQANY, A COR'PQRATION OFMASSACHUfiETT COMPRESSQB-UNLDENG MEANS Application filed Febrnaryfifi,MM. Serial Na'QMflW.

My invention relates to compressor unloading means.

An object of my invention is to provide an improved compressor unloadingmeans & and more especially an improved compressor.

unloading means of the auxiliary unloader type adapted to be used with acompressor having an intake t pe unloader and having for its particularunction the avoidance of shown for purposes of illustration. several.

v:forms which my invention may assume in practice.

In these drawings Fig. 1 is a central section through one illustrativeform of my invention.

Fig. 2 is a view of a compressor provided with this illustrative formof'my invention.

Fig. 3 is a view of a somewhat similar modification incentral section.

Fig. 4 is a fragmentary view on an enlarged scale illustrating theconnection of this last mentioned modification tothe high pressurecylinder of a compressor.

Fig. 5 is a central sectional view on the line 5'-5 of Fig. 6 through afurther modification.

Fig. 6 is a central sectional view through the mechanism of Fig. 5 takenon a plane corresponding to the section line 6-6 of Fig. 5.

Fig. 7 is a sectional view similar to that of Fig. 6 showing a furthermodification.

Fig. 8 is an elevational view of the high pressure cylinder of acompressor, illustrating the application of theforms of my inventionshown in Figs. 5, 6 and 7 thereto.

It will be understood that in the event that there is any leakage pastthe intake closure valve 1n a compound compressor, there will be veryundesirable consequences in the high -pressions that take place.

pressure cylinder unless some/special auxiliary means is providedtherefor, for the high pressure cylinder will pump down the pressure inthe intercooler to a partial vacuum notwithstanding any ordinary leakageand so, if such means is not provided, the high pressure piston willcompress air from a partial vacuumnp to full receiver pressure and avery hi h temperature will be developed due to t e number of com- Forthe purpose of preventing any such undesirable results, I have disclosedthe several different forms referred to above, each of which constitutesmeans for venting the ends of the highpressure cylinder of a compoundcompressor when the latter is running unloaded and as. soon as thepressure in the high pressure cylinder becomes a little aboveatmospheric pressure. I

In Fig. 2 there is shown a compressor provided with one of theillustrative forms of my invention, the same being generally designated1 and comprising'a low pressure cylinder 2 discharging to an intercooler3, with which a high pressure cylinder 4 is connected bya pipe 5.Mounted upon the higlh pressure cylinder 4 is an unloading mec anismgenerally designated 6 and including a casing 7 having chambers 8, 9which are connected by pipes 10' 11 respectively with the counterboresor othcr'suitable points at the lower-and upper ends of the cylinder 4.Between the chambers 8 and 9 is a third chamber 12 which communicateswith the surface 15 w ichprovides valve seats 16 and 17 respectivelysurroundin .a'series of ports 18 and 19 opening from t e chambers 8 and9 into chamber 13. Midway between the valve seats 16 and 17 there isarranged a seat 20 for a. poppet type valve 21 which is carried upon, astem 22 guided as at 23 and adapted to be moved by a piston 24.-reciprocab e in. acylinder 25 arr ed coaxial with the valve stem. Thiscylinder 25 is vented to the atmosphere 'by'means of a Ill port and isconnected at a point above the piston'24 with the intercooler by meansof a connection 26. A spring'27 surrounds the stem. 22 and acts betweenan abutment 28 on the casing 7' and a shoulder 29 at the lower end ofthe stem and the piston 24 on moving upwardly is adapted to engage thelower extremity of the stem and. raise it and with it the valve 21.Arranged upon 4 low pressure cylinder '2 is provided is closed sothatthe compressor has ceased to pump any fluid into the intercooler exceptsuch as may leak by the intake closure valve, it will be evident thatthe high pressure cylinder 4 will soon produce a partial vacuum in theintercooler 3 and as quickly as this happens the piston 24 will be movedupward against the pressure of the spring 27 by the atmospheric pressureacting upon its lower side with the result that the valve 21 will beunseated and the chamber 13 will be placed in free cornmunicationwiththe atmosphere throughthe passage 12. -Thereafter, as soon as there isany compression of the air which may leak ast the intake closure valveto even a sma l degree above atmospheric pres sure, the valve 30 or thevalve 31 'will be unseated' at such time as this pressure is reached andwill discharge the airto the atmosphere. As a result, it will be evidentthat the number of compressions which can take place is decidedlyreduced and the danger of burning of the lubricant and injury to theparts by high temperatures is totally prevented.

The form of my invention shown in Figs. 3 and 4 differs from that shownin Figs. 1 and 2 only in that the chan es in pressure in thehighpressure cylin er proper are relied upon to effect the operation ofthe atmospheric vent means. The structure,

with the exception of the means for eilectiug upward movement of thepiston which controls the atmospheric vent valve,.is identical withtheparts previouslydescribed and accordingly it is unnecessary torestate any part of this structure. It will be observed that instead ofemploying the connection 26 to the intercooler there is provided aconnection from each of the chambers 8 and 9 to the .s ace above thepiston 24, these connections ing respectively designated 38, 39 andbeing controlled by simple plate valves of thinflexible material" 40cooperating with seats 41, to prevent thepassage of amass? ing portions42- which serve to center them 7 while permitting the passage of fluidpast the valves when the latter are unseatedu Springs 43 are provided tomaintain the valves 40 normally seated, these being held in position byplugs 44.

Now considering the mode of operation of this form of my invention itwill be observed thatupon the closure of the intake controllin valve thepressure in the intercooler will speedily be pumped down to less thanatmospheric pressure and accordingly the movements of the high pressurepiston will produce a partial vacuum at the end of the cylinder awayfrom which the piston is moving at any given moment. When the pressureis thus reduced it is obvious that h it will be correspondingly reducedin the chambers 8 and 9 and accordin ly the pressure above the piston 24wil force the valves 40 off their seats and pass into the low pressurespaces at the ends of the cornpressor high pressure cylinder. As soon asthe pressure above the piston 24 is sufiiciently reduced the latter willmove upwardly and engage the stem 22 with the result that the valve 21will be unseatedc Thereafter, since there will be a artial vacuum duringeach suction stroke, t e piston will be maintained in raised positionuntil the compressor is reloaded notwithstanding the fact that there maybe pressures at the end of the compression strokes sufiiciently high tomomentarily unseat the valves 30 and 31, During the unloaded running ofthe com;- pressor, it will be evident that any pressure which may tendto be built up within either end of the compressor cylinder will be vented to the atmosphere very soon after it at tains a ressure equal toatmospheric pres sure and there will therefore be no possi bility of anundesirable range of compression which would result were these ventmeans not provided. -When the compressor is reloaded there will nolonger. be any tendency for fluid to flow from above the piston 24 tothe opposite ends of the cyl inder and 'asthe piston 24 15 not aperfectl tightlfit for its cylinder, the leakage throng leakage aroundthe stem 22 a so which would aid in this edect.

In Figs; 5, 6 and 8, a still further form of my improved construction isillustrated, w 11 e in Fig, 7 the structure is substantially the same asthat in the figures just menone end of the high pressure cylinder istioned, but there is a small" change which will be noted. In thesespecies of my invention it will be observed that a relief valve isarranged at each end of the high pressure compressor valves comprisingcasings 51, which casings are supported by the pipes 52 which connectcertain chambers within the casings with the counterbores or othersimilar parts of the compressor high pressure cylinder. Within thecasings 51 there are arranged three alined chambers, respectively 53,54,

55, a discharge chamber 56 and a passage or communication chamber 57.The chamber 53 which is connected by the pipe 52 with spaced by a septum58 from the chamber 54,

this septum providing a valve seat 59 with p which a valve 60cooperates. The chamber 54 is separated by a septum 61 from thedischarge chamber 56, and passages 62lopening through a valve seat 63 inthe chamber 56 serve to conduct fluid from the chamber 54 into thechamber 56. Suitable sprin closed annular valves 65 yieldingly helclosedby transversely flexed springs 66 normally close the communicationbetween chambers 54 and 56. Atmospheric dichar passages '67 lead fromthe chambers 56. T e valves 60 are connected b chambers 55, these istonsbeing normally held in the position s own in Fig. 5 with the valve 66seated upon itsseat 59 by springs 70. The space within the chamber 55above the piston communicates by way of the passage 57, a port 71,avalve chamber 72, and

. the port 73 with the space 53. Within the valve chamber '72 is a valveseat 74 with which a plate valve 75 of the t pe previously describedcooperates, whic valve is normally maintained seated by the spring .76and serves to permit flow from, but not towards, the chamber 55.

From the description given it will be at once apparent how thismechanism operates, when it is observed that there is an opening 77admitting atmospheric pressure to the lower side of the piston 69.Assume that the compressor is unloaded and that a partial vaccuum isdrawn in one end of the high pressure cylinder during one stroke of thepiston. This will cause thevalve 75 to be unseated by the pressure inthe passage 57 and chamber 55 and if the compressor continues to rununloaded, the pressure above each piston 69 will be reduced to such anextent that the pistons will move 11 wardly while the valves 75 willmaintain the pressure less than atmospheric in. the passage 57Accordingly upon the discharge,

strokes, it will at once result that the ressure" in the chamber shouldit excee atmospheric will be free to pass the valve 60 and enter thechamber 54 whence it may cylinder, these relief.

stems 68 with pistons 69 which are reciprocable in the passthrough ports62, valves 65 and so to the atmosphere through the opening 67.

Each end or" the cylinder-herein provides its own unloading mechanism.The valve 65 prevents back flow of air into the cylinder.

. As to the form of this mechanism shown in Fig. 7 it differs from thatshown in Fig.

free movement relative to the stem. Theeneral mode of operation is,however, identical with the form shown in Figs. 5, 6 and 7, Here also itwill be observed that the movement of the piston to effect the closureof the valve 60 is accomplished by reason of leakage past the pistons oralong the stems 68 or 68".

In connection with Figs. 5, 6, 7 and 8 it may be noted the chambers 57of the mechanisms at the opposite ends of the high pres sure cylindermay be connected b a pipe connection 79 (see Fig. 8), this being donefor the purpose of effecting the unloading at the opposite ends 'of thecylinder uniformly.

their respective pistons 24, 69 and 78 must be selected-so that theproduct of the efiective area of the pistons multiplied by thedifference between atmospheric pressure and the sub-atmospheric ress ureproduced as a. result of -unloading o the low pressure cylinder willexceed the product of the pressures valves Q1 or 60 multiplied by theeffective area of those valves. The present drawings are illustrative ofpositional relations, and changes appropriate to the conditions ofoperation are to be made in accordance with the foregoing principle.

In all the forms of my invention it will be observed that means isprovided of very simple construction which automatically takes care ofthe condition which may grow out of a. leaky intake closure valve andwhich results' in a really complete unloading of the compressor and theprevent-ion of any possible in'ury due to high temperatures.

While I ave in this application specifically described several formswhich my inven-' tion may assume in practice, it will be understood thatthese .forms of the same are shown for purposes of illustration and thatthe invention may be modified and embodied in various other formswithoutv departing from its spirit or the scope of the appended claims.What I claim as new and desire to secure by Letters Patent is:

1. An unloading mechanism comprising a casing provided with a chamberwhich has an outlet to the atmosphere, a valve opening against fluidpressure in said chamber forcontrellin said outlet member controllin 25acting during loaded operation upon the v tainin the outlet valve, meansfor normally mainsaid outletvalve closed, and means for su jecting saidmember to subatmospheric pressure to efiect movement thereof to .openthe outlet valve includingcheck' valve controlled passages adapted forconnection to the opposite endsol a cylinder.

2. In a compressor unloading mechanism comprising a casing having achamber adapted for communication with one end of a compressor cylinder,a chamber in constant communication with the atmosphere, a chamberintermediate said first and second mentioned chambers, a check valveopening. toward the second mentioned chamber controllin communicationbetween said second and third mentioned chambers, a valve controllingcommunication between said first and; third mentioned chambers, a fourthchamber, a piston therein operative to efi'ect opening of said secondmentioned valve, and a check valved connection between said pistoncontaining chamber and said first mentioned chamber.

3; In an unloading mechanism comprising a casin having a chamberprovided with an atmosp eric vent, chambers at the opposite sides ofsaid first mentioned chamber adapted for connection with the o positeends of a compressor cylinder, a c amber communicable with all three-ofsaid previously mentioned chambers, check valves openin toward said lastmentionedchamber control ing the communication therewith of said secondmentioned chambers, a valve controlling communication between saidfourth chamber and said first chamber, and means operativeto open saidvalve.

4. In an unloading mechanism com rising a casing having a chamberprovide with an atmos heric vent, chambers at the oposite si es of saidfirst mentioned chamr adapted for connection with the opposite ends of acompressor cylinder, a champ with an atmospheric vent, chambers at theher communicable with all three of said previously mentioned chambers,check valves opening toward said last mentioned chamber controlling thecommunication therewith of said second mentioned-chambers, a valvecontrolling communication ing said last mentioned side to pressuregreater than and less than atmospheric. 5. In an unloading mechanismcompris mg a casing having a chamber provided opposite sides of saidfirst mentioned chamber adapted for connection with the opposite ends ofa compressor cylinder, a chain manner her communicable with all three ofsaid previously mentioned chambers, check valves opening toward saidlast mentioned chamsaid valve including a piston constantly subjected onone side to atmospheric pressure, a spring adapted to oppose movement ofsaid piston, and means for intermittently subjecting the opposite sideof said piston to pressures equal to and less than atmospheric.

6. In an unloading mechanism comprising a casing having a chamberprovided with an atmospheric vent, chambers'at the opposite sides ofsaid first mentioned chamber adapted for connection with the oppositeends of a compressor cylinder, a chamber communicable with all three ofsaid previously mentioned chambers, check valves opening toward saidlast mentioned chamber controlling the communication therewith of saidsecond mentioned chamhere, a valve controlling communication betweensaid fourth chamber and said first chamber, and means operativeto opensaid valve including a filth chamber, a piston therein subjectedconstantly on one side to atmospheric pressure and alternately subjectedon its other side to ressures equal to and less than atmospheric andalso including check valved connections between said second mentionedchambers and said filth chamber. 7

'Z. An unloading mechanism, adapted for connection to a compressorcylinder, com rising valve means adapted to efiec't an an cod ingcontrolling liinction for a compressor, means whereby said valve isalways maintained in an open position while the compressor is unloadedto permit fluid in connected compressor to be discharged to atmosphere,and a plurality of valves for preventing baclr fiow of fluid to the3lllpressor while unloaded.

8. A compressor unloading mechanism comprising a casing having separatevalves posits ends of a compressor cylinder with which said casing isadapted for connection, valve means therein for controlling discharge tothe atmosphere from said ends, and vacuum responsive means therein 'l'oractuating said latter valve means. a 9. A compressor unloading mechanismcomprising chamber forming means adapt ed for communication with acompressor cylinder, means therein for controlling disc arge o'l lluidto the atmosphere from the cylinder to which it is connected aid to ellfeet unloading thereof, said latter means including a plurality ofvalves opening intill lllti lllli Hill . port, a member controlling saidlatter valve,

- inder,

wardly of said chamber forming means, one of said plurality of valvesbeing a check valve adapted to trap fluid pumped into said chamberforming means from said cyl- ,10. A compressor unloading mechanismcomprising chamber forming means adapted for communication with acompressor cylinder and adapted to be subjected to pressure existing inthe cylinder with which it has communication, means for controlling theunloading of said compressor including a plurality of valves openinginwardly of said chamber forming means, one of said plurality of valvesbeing a check valve for interrupting return flow from said chamberforming means to said \cylinder.

. 11. A compressor unloading mechanism comprising chamber forming meansadapted for communication with a compressor cylinder and adapted to besubjected to pressure existing in the cylinderwith which it hascommunication, means for controlling the unloading of said compressorincluding a plurality of valves opening inwardly of said chamber formingmeans, and means whereby one of said valves is adapted to be seatedwhile the other is open.

for maintaining said latter valve closed, and means for sub ecting saidmember to subatmospheric pressure produced by said compressor cylinderto efiect movement thereof to open said latter valve.

In testimony whereof I afiix my signature.

HALBERT B. HALVORSEN.

12. A compressor unloading mechanism comprising a casing having achamber adapted for communication through a check valve controlledpassage witha compressor cylinder and through a port to the atmosphere,a valve opening against fluid pressure in said chamber for controllingsaid means for'normally maintaining said latter valve closed, and meansfor subjecting said member to sub-atmosphericpressure to ef- 7 feetmovement thereof to open said latter valve.

13. A compressor unloading mechanism comprising a casing having achamber adapted for communication through a check valve controlledpassage with a compressor cylinder and through a port to the atmosphere,a valve opening against fluid pressure in said chamber for controllingsaid port, a member controlling said latter valve, means for maintainingsaid latter valve closed, and means for subjecting said member tosub-atmospheric pressure rotluced by said compressor cylinder to e ectmovement thereof to open said latter valve when said compressor isunloaded.

14. A compressor unloading mechanism comprising a casing having achamber adapted for communication with both ends of a compressorcylinder, a check valve adapted to interrupt return flow to each end ofsaid cylinder from said chamber, said chamber having a valve controlleddischarge to the atmosphere, said latter valve opening against fluidpressure in said chamber, a member controlling said latter valve, means

